I don't buy safety/medical products from Amazon. There was a time (maybe even today still) where those products go into a big bin with no verification of who the actual supplier was (1st vs 3rd party). I don't know how to verify if the issue has been resolved today, but life-critical items such as tourniquets, meds, etc. are expected to be 100% made by the supplier. Unfortunately, the money in the industry is so big that "cheap Chinese knockoffs" are being sold as high-quality replicas, even though they may not meet all the required specs.
There were many cases a few years ago of people buying branded tourniquets, only to be sold fake ones. The item looked genuine, but the integrity of the plastic could not maintain the pressures needed and broke. An emergency is not the time to realize that mistake.